<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

    <style>
        .active{
            color: green;
        }

        .error{
            color: red;
        }
    </style>
</head>
<body>
<script src="https://unpkg.com/vue@next"></script>
<div id="app">
    <span :class="[isSafe?activeClass:'', isSafe?'':errorClass]">Show Me</span>
</div>
<script>
    const vueOpt = {
        data(){
            return {
                isSafe:true,
                activeClass: 'active',
                errorClass: 'error'
            }
        },
    }

    Vue.createApp(vueOpt).mount('#app');


</script>
</body>
</html>
